Organic light emitting diode (OLED) display panels have become one of the hot topics in the research field of flat panel display panels today, and compared with liquid crystal displays (LCDs), the OLED display panels have the advantages of low energy consumption, low production cost, self-luminescence, wide viewing angle, fast response speed, etc. Currently, OLED display panels have begun to replace traditional LCD display panels in the products in display field such as mobile phones and digital cameras, and are expected to become the mainstream choice for the next generation of display panels.
With the development trend of display panel for becoming thinner, higher-resolution, intelligent, and energy-saving, the use of touch screen panels has become more and more widespread. Currently, because an in-cell touch panel comprises its touch elements inside the display panel, not only can the overall thickness of the module be reduced, but also the production cost of the touch panel can be greatly reduced, and this type of touch panel is favored by major panel manufacturers.
There are three main types of in-cell touch panel: resistive touch panel, capacitive touch panel, and optical touch panel. The implementation of resistance touch panel and capacitive touch panel is very difficult due to the limited process of the OLED, so people turn their attention to the solution of optical touch screen panel. However, optical touch screen panels also have problems. For example, if active modulation light is used to achieve the function of touch, it is better to use the OLED panel's own light emission, but because the light intensity in display produced by the touch screen panel changes over time, the touch amplitudes obtained under different display states of screens are different, so the accuracy of the touch position determination is greatly affected.